Evolution of human intelligence

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Evolution of Human Intelligence

Brain Size and Structure: Key Factors in Intelligence Evolution

The evolution of human intelligence is closely linked to changes in brain size and structure. Primates, elephants, and cetaceans are considered more intelligent than other mammals, with humans surpassing great apes in cognitive abilities. Key brain properties associated with intelligence include the size of the brain, cortex, and prefrontal cortex, as well as the degree of encephalization. However, the number of cortical neurons and conduction velocity are more accurate indicators of intelligence. Humans possess a higher number of cortical neurons compared to other mammals, which contributes significantly to their advanced cognitive abilities.

Genetic Contributions to Intelligence

Genetic research has identified numerous genes associated with the evolution of human intelligence. Studies combining inter-species and intra-species genetic variations have pinpointed 40 strong candidate genes involved in this process. These genes show distinct expression patterns in the cerebral cortex, particularly in neocortex tissues, which are crucial for higher-order cognitive functions. This genetic differentiation between humans and other species underscores the role of specific genetic changes in the development of human intelligence.

Dopamine's Role in Cognitive Evolution

Dopamine, a key neurotransmitter, has been proposed as a central factor in the evolution of human intelligence. The expansion of dopaminergic systems in early hominids is believed to have enhanced cognitive skills such as motor planning, working memory, cognitive flexibility, abstract reasoning, and temporal analysis. These skills were crucial for survival strategies like chase-hunting, which required advanced cognitive abilities to counteract hyperthermia during endurance activities. This dopaminergic expansion may have also contributed to increased brain size and complexity.

The Cognitive Niche and Social Intelligence

Human intelligence is thought to have evolved as an adaptation to a knowledge-using, socially interdependent lifestyle, known as the "cognitive niche." This theory suggests that humans developed advanced reasoning abilities to overcome environmental challenges through tools, coordinated hunting, and plant detoxification. These cognitive skills are further enhanced by social interactions, which drive the evolution of cooperation and complex social behaviors. The ability to understand and predict others' mental states, known as theory of mind, is a specialized form of intelligence that has evolved in humans, setting them apart from other species .

Environmental and Evolutionary Pressures

Environmental factors such as temperature and evolutionary novelty have also played significant roles in the evolution of human intelligence. Cold climates and harsh winters may have selected for individuals with higher intelligence, as these conditions required advanced problem-solving skills for survival. Additionally, the evolutionary novelty of new environments likely spurred the development of general intelligence, enabling humans to adapt to diverse and changing habitats.

Conclusion

The evolution of human intelligence is a multifaceted process influenced by brain structure, genetic changes, neurotransmitter systems, social interactions, and environmental pressures. The combination of these factors has led to the development of advanced cognitive abilities that distinguish humans from other species. Understanding these evolutionary mechanisms provides valuable insights into the unique aspects of human cognition and the complex interplay of biological and environmental influences.